The subject invention concerns an arrangement in working lamps of the kind comprising an upper pivotable arm supporting the light fittings proper, and a lower pivotable arm which is arranged for pivotal movements about a horizontal shaft provided in a housing at the lower end of the lower arm, said pivotable arms being interconnected by a segment and hingedly connected thereto for pivotal movement, each about its respective pivot shaft.
Working lamps for close-range illumination of working areas, such as desks, working benches, machines and the like are usually provided with pivotable arms of the above-mentioned kind in order to maximize the range and positions of adjustment of the lamp. Since in this kind of lamps the light fittings are normally positioned at the extreme end of the upper pivotable arm, i.e. at the remote end from the point of attachment of the lamp, the lamp has a tendency to buckle up about its attachment.
It is known to arrange the upper and/or the lower pivotable arm as double parallel rods including spring means to counter-act the moments tending to tilt the pivotable arms supporting the fittings. The parallel rods form levers with which the springs can cooperate. In addition, this arrangement has the advantage that when the lower arm is lowered to move the light laterally, the angle of the light fittings to the illuminated surface remains substantially the same.
Similar types of lamps are known showing combinations of frictional joints and lever-arm joints and springs cooperating therewith.